The present invention relates to an apparatus for automatically inspecting required characteristics of powdery products, for instance, powder of resins such as vinyl chloride resins, ABS resins and MBS resins and other powdery products such as powdery foods, for the purpose of quality control thereof.
When preparing, for instance, vinyl chloride resin powder and forwarding the products from a manufacturing plant, the quality control of the product is carried out, upon manufacture of the products, by inspecting samples thereof for predetermined properties, recording the results in a quality control table, sending back the table to the manufacturing plant to feedback the results into the manufacturing conditions of the products and, upon forwarding the products, a quality control table is commonly attached to the product in order to guarantee the quality thereof for user's convenience. The name of product, the kind thereof, the name of manufacturing plant, the manufacturing date and the number of manufacturing lot are recorded in the former quality control table and, on the other hand, the name of product, the kind thereof, the number of manufacturing lot and optionally the destination or the consignee are recorded in the latter quality control table.
For this reason, there is a diversity of items for quality inspection. For instance, the items for quality control of vinyl chloride resin powder include average degree of polymerization, bulk density, contents of volatile components, particle size distribution, amounts of foreign substances, amounts of remaining monomers, amounts of plasticizers absorbed and optional other items. An inspector appropriately selects items required for each sample (product) among the foregoing items required for quality control in accordance with a table including the foregoing items as well as other conditions such as the applications of the products and the destination or the consignee, collects necessary amounts of the samples and analyzes them using separate apparatuses required for the determination of these selected items. The results of such analysis are compared with the quality standards and judged. The results thus obtained are stored after recording in a report in the form of a quality control table or recording in a ledger.
In the conventional quality control system discussed above, however, items to be inspected often differ from sample to sample, it takes a long time since an inspector selects items to be inspected, collects and distributes samples to inspect them for the selected items and the inspector would sometimes make a wrong selection of items to be inspected. Moreover, results obtained through such inspection sometimes vary depending on inspectors. When the powdery product to be inspected is, for instance, a resin such as a vinyl chloride resin, an ABS resin or an MBS resin, the powdery product is liable to be charged in itself and accordingly, resin particles repulse each other due to electrostatic charges present on these particles. This makes the determination of the bulk density and the amounts of foreign substances included therein very difficult.